In Abramowski et al. U.S. Pat. No. 5,124,395, a non-ozone depleaing, non-flammable tire sealer and inflator composition is disclosed using as a propellant/inflator 1,1,1,2-tetrafluoroethane, sometimes known by the tradename of HFC 134a. HFC 134a was developed as a replacement product for Freon-type products in formulations such as tire inflator formulations stored in an aerosol can with a valve, where a tire can be inflated by attaching the valve of the can to the valve of a tire, and allowing the pressure in the can to inflate the tire, with the contents sealing the leak in the tire.
Particularly, HFC 134a was developed as a replacement product for chlorofluorocarbon propellant/inflators. It can be seen that HFC 134a is a chlorine-free fluorocarbon. Chlorofluorocarbons such as CFC-12 (dichlorodifluoromethane) are undesirable for use because of their capability of attacking the ozone layer of the atmosphere.
Other propellants for tire inflator formulations have been considered such as butane and propane. However, these propellants are flammable and thus can be dangerous when used in tire inflator formulations. Thus, HFC 134a has been widely considered as a potential substitute for these other propellants in a variety of uses including tire inflator formulations, serving as an aerosol propellant and an inflator in desired formulations which do not harm the ozone layer, and which are nonflammable.
Other prior art tire sealant and inflator systems are disclosed in Magyar et al. U.S. Pat. No. 4,501,825, which discloses a tire sealant and inflator system which comprises from 20 to 40% of a resin, 20 to 40% of a latex sealant, and 2 to 20% of an alkylene glycol, mixed with a propellant comprising 60% dichlorodifluoromethane and 40% dichlorotetrafluoroethane.
Fang U.S. Pat. Nos. 5,618,912 and 5,705,604 show various tire sealer and inflator compositions using a non-flammable propellant/inflator having an ozone depletion potential of zero (i.e. HFC 134a) and also incorporating a petroleum residual resin sealant, among other ingredients.
As one technical problem, the vapor pressure of HFC 134a at 130 degrees F. is 198-199 psig. This is well above 180 psig limit criteria for aerosol cans of 2Q type under DOT regulations. While the above patents have listed various vapor pressure reducing additives which may be provided to the formulation, the specific additives taught in the prior art are less effective than desired.
In accordance with this invention, vapor pressure reducing additives are provided to sealer and inflator compositions which have increased effectiveness, so that lesser amounts of the additives are required, resulting in a significant cost reduction to formulations making use of the invention of this application.